SoilS 101:A practical approach

Kevin MariniUCCE Placer/Nevada Counties

SoilS 101:agenda

Soil Basics

Soil Fertility (how plants and soil interact)

Soil Food Web

Fertilizers/Amendments

SoilS 101:a Quote by CharleS e. Kellogg, uSda 1938

“Essentially, all life on this planet depends on the soil…There can be no life without soil and no soil

without life…they have evolved together.”

Step 1:

Start with Soil basics

Why learn about Soil?• It’s what plants grow in!

• To determine how to water/fertilize plants

• To assess problems (disease, nutrient deficiencies, etc…) related to these plants

• To understand how to support the living organisms there

• Because playing with soil makes us happy!

Your Soil…exposed!

Soil = Minerals, Organic Matter, Air Water, and ??????

An ideal garden soil is fertile, deep, easily crumbled, well-drained and fairly high in organic matter and…

Full of Life!

Where does soil come from?

Rocks!

To begin with…

Your Soil…exposed!

Mineral content is a result of dynamic processes involving parent material (rock), biotic activity, topography, time, climate, and more!

Your Soil…exposed!

So where do I find out about my soil’s parent material???

NRCS Web Soil Survey: http://websoilsurvey.nrcs.usda.gov

Web soil survey factoids

• Drainage• Slope• Topography• Water features• Crop Worthiness• Buildability• More!!

Your Soil…exposed!

Soil Types

Officially Classified by:

1. Depth2. Color3. Soil Texture4. Soil Structure

Your Soil…exposed!

Soil Types

Officially Classified by:

1. Depth2. Color3. Soil Texture4. Soil Structure

Your Soil…exposed!

Soil Texture:Relative proportions of

Sand, Silt and Clay

In general, you are not going to change or alter your SOIL TEXTURE…

What’s your soil texture?1) jar test, 2) soil texture by

feel

Your Soil…exposed!

Your Soil…exposed!

Soil Texture:

Why is it important to

know?

Your Soil…exposed!

Soil Structure:How soil particles are grouped together in

aggregates

The structure influences air and water movement through soil or “PORE SPACE”…YOU CAN IMPROVE Your Soil Structure!!

Determine Your Soil Structure:1. Shovel test

Determine Your Soil Structure:2. Soil Drainage or PERC test

To test drainage, dig a whole about 1 foot deep. Fill with water and allow it to drain completely. Immediately refill the pit and measure the depth of the water with a ruler. 15 minutes later, measure the drop in water in inches, and multiply by 4 to calculate how much water drains in an hour.

--Less than 1 inch per hour is poor drainage, indicating the site may stay wet for periods during the year. Plants that don't tolerate poor drainage will suffer.

--1 to 6 inches of drainage per hour is desirable.

--Soils that drain faster than 6 inches per hour have excessive drainage, and you should consider choosing plants that tolerate dry conditions and "drought" soils.

Your Soil Structure:

• Good Soil Structure = holds water and air, good pore space

• Bad Soil Structure = holds less water, lacks air, poor pore space

Your Soil Structure:

• The Soil Solution – nutrient availability

Your Soil Structure:How can you improve it?

• Avoid compaction of planted areas –reduced tillage, permanent paths, mulch

• Add organic matter to the soil – compost!!• Grow cover crops!• Proper watering and fertilization• Build and Nurture Soil Food Web

Soil Texture by Feel Exercise

Step 2:

Soil fertility

Understanding Your Soil

Soil Fertility:

Clay particles AND organic matter

hold onto nutrients and water

in the soil.

Let’s start with clay…

Understanding Your SoilSoil Fertility:

Clay particles are soooimportant!!

•Small particles with a lot of surface area

•Clay particles are negatively charged

•Attracts/holds water molecules

•Repels negative charges

Understanding Your SoilSoil Fertility:

Organic Matter breaks down into stable humus,

which holds water and nutrients just like clay

particles.

It also acts as “glue” and helps particles aggregate

and is food for soil organisms (humic and

fulvic acids).

Understanding Your SoilThe amount of CATIONS that can be held by soil (clay and humus) is the CATION EXCHANGE CAPACITY (CEC).

Understanding Your SoilAnd what about pH?

Understanding Your Soil•So, how do you figure out your CEC?

•How do you know what nutrients are in the soil to begin with?

Soil Analysis

Soil Analysis

Adding Amendments

Soil analysis results will help determine what amendments you add.

Good guideline but not 100% accurate as far as PLANT AVAILABLE nutrients.

Ongoing soil monitoring

Soil is the most species-richmicrobial ecosystem in the world!!!

Ag Land Prairie Forest

Organisms per gram (teaspoon) of soil

Bacteria 100 mil. -1 bil. 100 mil. -1 bil. 100 mil. -1 bil.

Fungi Several yards 10s – 100’s of yds 1-40 miles (in conifers)

Protozoa 1000’s 1000’s 100,000’s

Nematodes 10-20 10’s – 100’s 100’s

Organisms per square footArthropods < 100 500-2000 10,000-25,000

Earthworms 5-30 10-50 10-50(0 in conifers)

Soil Organism populations in healthy soils

Bacteria and fungal hyphae (USDA)

Nematode captured by the constricting rings of the predatory fungus Arthrobotrys anchonia.

Ciliates – a type of Protozoa in soil – sometimes called “soil salmon” – have an BIG appetite for soil bacteria

Soil Organisms – What do they do??• Decomposition of organic matter• Cycling of minerals and nutrients• Reservoirs of nutrients – “fertilizer bags”• Redistribution of minerals and nutrients• Sequestration of carbon• Degradation of pollutants, pesticides• Modification of soil structure• Biological regulation of pest species

Soil Organisms – Mycorrhizal Fungi

Soil Organisms – Mycorrhizal Fungi

Soil Organisms – Nitrogen-Fixing Bacteria

Bacteria are the only organisms capable of taking gaseous nitrogen and combining it with hydrogen to make ammonia.

Soil Microbes – lab analyses

Counting •Direct counts of individuals

•Plate counts of colonies

Activity levels •Respiration (CO2 production)

•Nitrification rates

•Decomposition rates

Cellular constituents •Biomass C, N, or P

•Enzymes

•Phospholipids

•DNA and RNA

Threats to HEALTHY SOIL

•Soil Erosion•Excessive Tillage•Synthetic Fertilizer•Overwatering•Soil Compaction•BARE SOIL

Simple Way to Improve Soil:Compost and Mulch!!!

Mulch vs. Compost

● Mulch = Organic or inorganic material spread on the soil surface

● Compost = Rotted organic matter made from plant material and/or manure– Usually incorporated into the soil

Mulching with Wood Chips

Potential Benefits of Mulch

● Reduces weeds & erosion● Insulates roots from temp. extremes● Conserves soil moisture ↑ root growth● Increases microbial activity● Increases water penetration● Improves plant establishment● Improves Soil Structure over time

Potential Problems with Mulch

● May prolong saturation in heavy soils– Favors root and crown rot

● May host plant diseases,insects, and nuisance fungi

● Some wood chips poor quality● Can’t see soil moisture● Time consuming to spread

Mulch Basics(Wood Chips)

● Softwood mulches (pine, cypress, etc.) last longest – less microbial feeding

● Keep mulch 6-12 in. away from the base of trees & shrubs when soil wet, poorly drained

● Application rate: Generally 2-4 in. deep– Fine = <2 in. Coarse = 4-6 in.

● Keep mulch on top of soil to prevent N tie-up

Mulch BasicsOther Types of Mulches

● Straw● Pine needles● Oak leaves● Plastic● Gravel

Working with Foothill Soils

What did you learn about our local soils??????